Tag Archives: urban tissue

Sometime last year this website attracted the attention of several members of the International Network for Traditional Building, Architecture and Urbanism, an organization sponsored by the Prince of Wales Foundation in order to support and renew traditions of construction. While this organization does great work to preserve the techniques of traditional building cultures, they have yet to define what the traditional urbanism of their name really implies. The importance of such a definition I believe to be primordial. If modern planning measures continue to be adopted from one country to the next, any traditional technique of construction will become irrelevant, as they have in western industrialized (and post-industrialized) countries.

This all became obvious when a miniature controversy erupted and swept through the various internet discussion groups and blogs of the community over a proposed redevelopment of the Chelsea Barracks in London’s Chelsea borough. An old modernist military installation was to be torn down and replaced by its new owner, the Emir of Qatar, with a new modernist megahousing development designed by Lord Rogers. There was nothing particularly interesting about this Rogers design, but Lord Rogers having written the plan of London, a plan that specifically calls for better design, it made sense that a Rogers design would be swiftly approved by the planning authorities. Hiring Rogers was the most risk-free option available for a multi-million pound development project.

Getting wind of this, and noticing that the Rogers design was an unremarkable piece of rehashed modern housing, the Prince of Wales hired his preferred architect Quinlan Terry to sketch up a counter-proposal that was more in harmony with the architecture of the landmark Royal Chelsea Hospital across the street from the barracks, which he then proposed to the Emir of Qatar through his personal relationship with him. The Emir, alien to the local culture and uncertain of what London considers to be “good design”, then decided to dump Rogers and re-think the development.

The Prince of Wales and Quinlan Terry counter-proposal

Lord Rogers' Chelsea Barracks redevelopment proposal

I am not going to analyze the controversy from all of its fascinating angles, such as the design quality of the architecture, Lord Rogers (of the House of Lords) teaming up with British Republicans to denounce the monarchy’s interference with civilian life, or the absence of affordable housing in Chelsea. I am interested in only one question: is this traditional urbanism?

At first sight, the Terry design is reminiscent of the 18th/19th century style of palatial construction in Europe. (In fact one of the “blocks” features echoes of Buckingham Palace.) In terms of authenticity, the proposal is flawless. The Rogers proposal is also a palace, although one with much fewer attractive qualities. But does Chelsea really need a palace?

Providing a response to that inquiry is precisely what a system of urbanism is supposed to achieve. The system in place for London unfortunately requires that one have enormous financial means in order to participate in any kind of development, and inevitably that implies that only large speculative development will be so much as imaginable. The Chelsea Barracks proposal is entirely a product of modern urbanism, and by intervening into that system, the Prince of Wales and other traditionalists are sanctioning the very thing they claim to be opposed to.

When I last covered Chelsea, I used its housing typology as an example of a linear, non-complex model of housing development. While linear housing is characteristic of the neighborhood, it is not the entire tissue of it. If we analyze the morphology of the neighborhood we find many clusters of housing rows, but these clusters do not necessarily repeat from one block to the next, and they are intermingled with other, uniquely programmed buildings of varying scale, the most prominent of which being the Royal Hospital. This means that, despite the neighborhood’s texture being only semi-random and not completely emergent, it performs at a remarkable level of complexity.

This kind of fabric is very common of British-American subdivision development during the 19th century. Here it is in a pure grid form in one of Montreal’s inner core “Plateau” neighborhoods.

We can observe that the middle of blocks is populated very differently from the major streets, despite the fact that they are not very different from a design standpoint. We don’t need to propose anything more complicated than self-optimization to explain this pattern. During development, housing builders would work from the center of blocks outwards, where there was the least perceptible traffic, and shops, churches and other activities located where there was the most traffic. The outcome is a complex tissue with perceptible characteristics, not only random noise.

In comparison, here is the texture of a new neighborhood in Las Vegas (Henderson), Nevada.

It is the same housing model repeated a thousand times, some lots facing backwards from the main roads. This new neighborhood might as well define linear development processes. The only feature of this neighborhood is the house, and so it can only function at any level of complexity by ejecting its residents out into town for any activity.

Of course some might say this is not a fair comparison. Those old neighborhoods are old, and therefore have had a long time to achieve maturity. But a neighborhood maturing implies that the neighborhood is planned to have a life cycle taking place in time, of which the early stage of growth is critical to its final morphology. What did a young, new neighborhood look like in 19th century British-American urbanism? It consisted mostly of very large lots of gardens and other large events (such as, for example, a Royal Hospital). These new neighborhoods were advertised as a pastoral refuge from the city. Look at this engraving of Milwaukee’s outskirts in 1858.

Its overall density is much lesser than that of Las Vegas new neighborhoods, and it has a distinctively pastoral quality. Yet what happened to those traditional neighborhoods was often that, very rapidly (the span of 2-3 decades) they became very dense urban neighborhoods, at which point the rate of new growth plunged and the fabric remained stable.

In less than two decades the neighborhood was populated from a pastoral grid dominated by the campus of Columbia University to the dense, New York-style neighborhood it remains today. In these examples, growing a mature neighborhood was intrinsic to the development process adopted, and once this process wound down there was very little left to change to it. The neighborhood was mature because it had reached its equilibrium with the socio-economic context. Correcting deficiencies is what is meant by a neighborhood maturing, and developing a mature city implies that one is avoiding mistakes during its development. If we are employing a development model that is set in advance, no mistake can be either corrected or avoided during production.

Notice then that in traditional neighborhoods, the construction of mass-produced housing came last, after the neighborhood had established itself as a socio-economic system at the fringe of an existing city. Because of this, the mass-produced housing is a complement to that tissue, and contributes to the established complexity of the neighborhood, even super-charging it with population density. This not only ensured that there was no environmental alienation for the new residents, but also that there was a limit to how much repetition there could be from housing builders.

In modern urbanism we require all new developments to be programmed for a certain type of use, whether we are building a housing subdivision, an office or industrial zone, or a “mixed-used” development. If this is not know and debated in public, no development project can be approved. Only when a proposal has gone through this ordeal can anything be built, and making changes involves going through the process again, so the developers just subsidize the mistakes, or leave certain parts of the plan unrealized and a gaping hole.

In traditional urbanism this is never necessary. In fact it is possible for entire blocks to be left as pasture or gardens, creating an ultra-low density urban tissue. Only as further development becomes truly needed are these blocks transformed into housing and other programs. A critical difference is that no planning permit or approval is necessary to further develop a neighborhood. Instead the residents have an envelope of building rights set in building codes, and everything within that space is considered to be automatically approved. Because of this the development of a neighborhood can be undertaken in a large number of successive decisions, where the next building to be added is not only determined by the citywide market but also by the current state of the neighborhood. This in turn allows a local community and economy to grow, which is absent from modern developments.

This is all very interesting for new neighborhoods, but how would that apply to a small urban redevelopment site in the middle of a centuries-old neighborhood? Clearly we aren’t going to be building up from pastures. This is where a “new” traditional urbanism becomes relevant, as we need to invent a new process that restores the features of traditional urbanism, but can also function in the context of mature cities and modern structural requirements.

Although the redevelopment of a large urban block is usually undertaken as a large real-estate project, it can also be considered as a nested process of urbanism (urbanism within urbanism). Much like the city-wide process of urbanism is characterized by regulations intended to achieve equilibrium, the redevelopment of a block of the city should also be designed as to achieve its equilibrium with the city as a whole but (and here is the defining characteristic of a traditional urbanism) also within itself. This is what does not happen in linear development processes such as housing subdivisions, or 19th century housing terraces. They provide equilibrium with the larger scale, but amongst themselves they provide no complement. For this reason, although you’re likely to see a lot of some housing model repeated in one place, you’ll rarely ever see it used again elsewhere. Mass-production does not work for buildings the way it does in automobiles.

Time and interaction are the critical factors. The reason large-scale development like the Rogers and Terry proposals get approved and built is that everything must be conceived and approved in one step. The architectural design is rushed in order to make proposals as soon as possible. The form can’t evolve over the course of development. This process is justified by the need to control the architectural character of the city, but it is not necessarily so. It only follows from controlling architectural character because we rely on static information systems and processes to conduct building. In fact, many of the traditional building techniques that preservationists are attempting to preserve do not translate into modern information systems (building plans). If instead of drawing the full plans, the proposals simply supplied the component patterns and a parameter space for them, then there could be an infinite variety of different instances of these patterns populating the new space, all fitting a particular need and applying a specific method of returning to equilibrium. If we wanted to release control even more, we could define some buildings from the neighborhood as models and whatever patterns they featured as automatically approved. And seeing as this is the 21st century, we could define these patterns inside software that could randomly generate any possible permutation, such as the City Engine.

With the architecture out of the way, there would only need to be a fixed design for the frame of spaces around which the urbanization will take place. Grids are flat and unspecific, and so a good project will have a place structure that creates inequalities of movement. (Even New York’s grid has subtle inequalities in the short-blocked avenues and long-blocked streets, creating vastly different spaces in character.) Crescents, squares and alleys on a completely open surface should be the extent of planning a new neighborhood, and it will be important that this design have value all of its own. It is quite possible, for whatever economic reasons, that only part of the surface will be built, or even that nothing will be built. A good urban design must work in all states, including with nothing on it. Remove the buildings from the Terry proposal and there is still a rather interesting landscape. The Rogers proposal, without its buildings, has nothing. Terry is therefore much closer to the goal.

Negative space in modern plots

In the final step, how does the developer make money? Sustainable development, after all, has to be profitable in order to be sustainable. In a traditional city, plots were subdivided over time as the need arose. In a modern city lots are defined as a standard shape, and then later sold off for some standard price. This approach has the unfortunate side effect of creating a lot of negative space. The developer of the Chelsea Barracks could instead sell or auction off space as an elastic product. The first buyer would choose the first spot on the open surface, in relation to the hierarchy of the urban grid. The second buyer would place himself in relation to the urban grid and the first buyer. These buyers at first would come from long-time residents of the neigborhood aware of some particular way of extending the neighborhood, but unable to find a lot a space at the right size before this project became open to the public. This process would continue until all the space had been consumed, and the end result would be that all buildings would be related to one another through the sales process. If the space was priced high enough, the later projects would only be initiated after the initial ones had been completed, and the impact of time would generate the demand for building programs complementing the initial projects.

In such a way the urbanism within urbanism would create its own socio-economic subsystem, would feature a randomly adapted but uniform architectural signature, and would complement and extend the external urban tissue.

While I’ve detailed a process for developing a small block within a city, this process is just as applicable for doing development of new cities, or new suburbs of cities. There are fewer constraints and difficulties involved in these other cases, which is why I wanted to use the example of the Chelsea Barracks site. Urbanisation is a universal phenomenon, and although the patterns change, the underlying principles are everywhere the same.

The qualities of an emergent city

The adoption of mass-production processes, or development, in substitution for spontaneous urban growth in the mid-20th century created for the first time a phenomenon of alienation between the inhabitants and their environment. While the physical features of spontaneous cities could be traced to complex histories of families, businesses, and organizations, the physical features of planned cities owe their origin only to the act of planning and speculation. This has severe consequences towards the sustainability of place as there will not grow any particular attachment by the residents, their presence there being only a temporary economic necessity and not the outcome of their life’s growth. Mass-production of the environment left people as nothing more than consumers of cities where they used to be their creators. A building culture was replaced with a development industry, leaving the landscape culture-less and with no particular sense of identity. This took place despite the evidence that a building which has a unique history and has been fitted to someone’s life, as opposed to speculatively produced, generates market value for that property. (Alexander, 1975) This is why, although the demolition of so-called “slums” to replace them with modern housing projects created a great deal of opposition against urban renewal programs, the demolition of the housing projects later on did not lead to a popular preservationist opposition. They were not the physical expression of any culture.

In additional to cultural patterns, spontaneous settlements also have a peculiar morphology that has not successfully been imitated by modern growth processes. Spontaneous settlement processes give individuals full freedom to determine the boundaries of their properties. Spontaneous settlement is one where total randomness in building configuration is allowed, with no pre-determined property lines acting as artificial boundaries. Buildings and building lots as such acquire general configurations comparable to cell structure in living tissues, unique sizes and boundaries that are purely adapted to the context in which they were defined. In the absence of abstract property boundaries, property rights are bounded by real physical limits such as a neighbor’s wall. (Hakim, 2007)

Very attractive spontaneous cities have a specific pattern of the urban tissue. It consists of similar vernacular buildings that appear very simple when considered individually, but produce a visually fascinating landscape when considered as a whole. This is a form of fractal geometry. In mathematics a fractal is a geometric object of infinite scale that is defined recursively, as an equation or computation that feeds back on itself. For example the Sierpinski triangle is defined by three triangles taking the place of one triangle as in figure 4.

Figure 4. A triangle triggers a feedback function that produces three triangles, which themselves trigger the feedback function to produce nine triangles, and so on. This process can unfold as long as computational resources can be invested to increase the complexity of the object.

The Mandelbrot Set is a much more interesting fractal that is defined as a simple recursive mathematical equation, yet requires a computation to visualize in its full complexity. When computing how many cycles of feedback it takes for the equation to escape to infinity for specific coordinates, figure 5 is the outcome.

Figure 5. The image on the right is a deeper magnification of the image on the left, produced with a narrower range of coordinates as the input of the Mandelbrot set’s feedback function.

In addition to its remarkable similarity to natural phenomena, this form of geometric order informs us of a very important law in geometry: a feedback loop that is fed through the same function will produce an ordered but unpredictable geometric pattern out of any random input.

This tells us why cities of vernacular buildings have such appealing geometric properties at the large scale, despite being often shabby and improvised at the scale of individual buildings. Shanties made of scrap metal and tarp look rough at the scale of the material, but because multiple shanties share the construction process and originate from similar feedback conditions they form an ordered geometric pattern with its specific “texture”. The same process takes place at other scales of feedback, for example the production of a door. Whether the input for one door is larger, taller, wider than another door, if the same production process is employed the two doors will contribute to the overall fractal order of the urban space. This law has been employed not only in traditional and spontaneous cities, but also for modern urban planning initiatives. In the New York City neighborhood of Times Square the structure of billboard advertisements is defined by a building code that determines their configuration in relation to the configuration of the building. The outcome is a unique tissue of advertisement billboards that has become more characteristic of the neighborhood than the buildings themselves, which are not produced by a shared feedback function.

Fundamentals of urban complexity

Christopher Alexander showed in A City is not a Tree (Alexander, 1965) that social and economic networks formed complex semi-lattice patterns, but that people who observed them limited their descriptions to a simple mathematical tree of segregated parts and sub-parts, eliminating connections in the process. (Figure 6 compares the structure of a tree and semi-lattice.) In attempting to plan for urban structure, a single human mind, without a supporting computational process, falls back on tree structures to maintain conceptual control of the plan, thus computing below spontaneous urban complexity, a phenomenon that is consistent with Wolfram’s theory of computational irreducibility of complex systems. (Computational irreducibility states that the only accurate description of a complex system is the system itself and that no abstraction or reduction to a simpler process is possible.) Nikos A. Salingaros later detailed the laws of urban networks in Theory of the Urban Web. (Salingaros, 1998) Network connections form between nodes that are complementary, and therefore the complexity of networks depends on an increasing diversity of nodes. Salingaros describes the urban web as a system that is perpetually moving and growing, and in order to do this the urban tissue has to grow and move with it. Consider for example the smallest social network, the family. Debate over accessory units or “granny flats” has intensified as normal aging has forced the elderly out of their neighborhoods and into retirement complexes, while at the other end of the network young adults entering higher education or the labor market vanish from a subdivision, leaving a large homogeneous group of empty-nesters occupying what was once an area full of children, and often forcing school closures (a clear expression of unsustainability).

Figure 6. A comparison of a tree pattern on the left and a semi-lattice pattern on the right. The tree structure is made of groups and sub-groups that can be manipulated separately from others. The semi-lattice pattern is purely random without distinct sub-parts.

These social networks grow more complex with increasing building density, but a forced increased in density does not force social networks to grow more complex. For instance the spontaneous settlements of slums in the developing world show remarkable resilience that authorities have had difficulty acknowledging. Because of squalid living conditions authorities have conducted campaigns to trade property in the slum for modern apartments with adequate sanitary conditions. To the authorities’ befuddlement some of the residents later returned to live in the slum in order to once again enjoy the rich social networks that had not factored in the design of the modern apartments and neighborhoods, demonstrating that the modern neighborhoods were less socially sustainable than the slums.

In commercial networks, space syntax research (Hillier, 1996), using a method for ranking nodes of semi-lattice networks, has shown that shops spontaneously organize around the multiple scales of centrality of the urban grid at its whole, creating not only commercial centers but a hierarchy of commercial centers that starts with sporadic local shops along neighborhood centers and goes all the way to a central business district located in the global center of the spatial network. The distribution of shops is therefore a probabilistic function of centrality in the urban grid. Because the information necessary to know one’s place in the hierarchy of large urban grids exceeds what is available at the design stage, and because any act of extension or transformation of the grid changes the optimal paths between any two random points of the city, it is only possible to create a distribution of use through a feedback process that begins with the grid’s real traffic and unfolds in time.

The built equilibrium

Although they may appear to be random, new buildings and developments do not arise randomly. They are programmed when the individuals who inhabit a particular place determine that the current building set no longer provides an acceptable solution to environmental conditions, some resulting from external events but some being the outcome of the process of urban growth itself. It is these contextual conditions that fluctuate randomly and throw the equilibrium of the building set out of balance. In order to restore this equilibrium there will be movement of the urban tissue by the addition or subtraction of a building or other structure. In this way an urban tissue is a system that fluctuates chaotically, but it does so in response to random events in order to restore its equilibrium.

This explains why spontaneous cities achieve a natural, “organic” morphology that art historians have had so much difficulty to describe. Every step in the movement of a spontaneous city is a local adaptation in space and time that is proportional to the length of the feedback loops and the scale of the disequilibrium. For spontaneous cities in societies that experience little change the feedback loops are short and the scale of disequilibrium small, and so the urban tissue will grow by adding sometimes as little as one room at a time to a building. Societies experiencing rapid change will produce very large additions to the urban tissue. For example, the skyscraper index correlates the construction of very tall buildings with economic boom-times, and their completion with economic busts. The physical presence of a skyscraper is thus the representation of a major disequilibrium that had to be resolved. (Thornton, 2005) The morphology of this change is fractal in a similar way that the movement of a stock market is, a pattern that Mandelbrot has studied. In general we can describe the property of a city to adapt to change as a form of time-complexity, where the problems to be solved by the system at one point in time are different from those to be solved at a later point in time. The shorter the time-span between urban tissue transformations, meaning the shorter the feedback loops of urban growth, the closer to equilibrium the urban tissue will be at any particular point in time.

Modern urban plans do not include a dimension of time, and so cannot enable the creation of new networks either internally or externally. They determine an end-state whose objective is to restore a built equilibrium through a large, often highly speculative single effort. They accomplish this by creating a large-scale node on existing networks. In order for such a plan to be attempted the state of disequilibrium in the built environment must have grown large enough to justify the immense expense of the new plan. This is why development will concentrate very large numbers of the same building program in one place, whether it is a cluster of 1000 identical single-family homes or a regional shopping mall, just like the skyscraper concentrates multiple identical floors in one place. Demand for these buildings has become so urgent that they can find a buyer despite the absence of local networks, the standardized building plan, or the monotonous setting. This is not as problematic for large cities for which a single subdivision is only a small share of the total urban fabric, but for smaller towns the same project can double the size of the urban fabric and overshoot the built equilibrium into an opposite and severe disequilibrium.

The mixed-used real estate development has attempted to recreate the sustainable features of the spontaneous city by imitating the morphology of sustainable local economic networks. It has not reintroduced the time dimension in economic network growth. Often this has resulted in a commercial sector that serves not the local neighborhood but the larger region first, consistent with the commercial sector being a product of large-scale economic network disequilibrium. In other developments the commercial sectors have struggled and been kept alive through subsidies from residential development, which is evidence of its unsustainability as part of the system.

Understanding such a place solely by the generic term “slum” ignores its complexity and dynamism. Dharavi’s messy appearance is nothing but an expression of intense social and economic processes at work. Most homes double as work spaces: when morning comes, mattresses are folded, and tens of thousands of units form a decentralized production network rivaling the most ruthless of Chinese sweatshops in efficiency. Mixed-use habitats have often shaped urban histories. Look at large parts of Tokyo. Its low-rise, high-density mixed-use cityscape and intricate street network have emerged through a similar Dharaviesque logic. The only difference is that people’s involvement in local development in Tokyo was seen as legitimate.

Building on what exists, rather than clearing it for redevelopment, may preserve not only the character of a place but also its economic vibrancy. In Dharavi, it would allow all residents to leverage their most precious asset: a place to live and work. Slum-rehabilitation projects in Mumbai often end up creating new slums elsewhere as they increase real-estate value in the places they redevelop.

In the movie, when the protagonists return to their childhood haunts, they find that multistoried apartments have replaced the old decrepit structures, giving the impression of urban mobility and transformation. What the camera doesn’t reveal are the enormous shantytowns hidden behind those glistening towers, waiting to be redeveloped all over again.

In many ways, Dharavi is the ultimate user-generated city. Each of its 80-plus neighborhoods has been incrementally developed by generations of residents updating their shelters and businesses according to needs and means. As Ramesh Misra, a lawyer and lifelong resident, puts it: “We have always improved Dharavi by ourselves. All we want is permission and support to keep doing it. Is that asking for too much?”

The film provides amazing cinematography of Mumbai, but what shocked me the most was the postmodern neoclassicist residential towers being built in the slum. They appear alien to the place, clashing with the natural, complex morphology of the neighborhood. That shows up in the google maps images also. It shows that employing modern building processes is a choice and not an inevitability, and it is a choice that can take away from the identity of a place. The people of Dharavi were insulted that their city was called a slum because they all had a hand in building it. They won’t be eager to defend the place when all its complex tissues have been replaced with tower blocks.

Until very recent times, a study entitled Julian of Ascalon’s Treatise of Design and Construction Rules From Sixth-Century Palestine might have been categorized somewhere in-between ancient history and archeology of architecture, if not relegated to the dusty shelves of legal scholarship. Although it deals with one of the most sought-after secrets of architecture, how to build the charming Mediterranean towns of Greece, Spain, North Africa, the Near East and many other places, this is not immediately obvious from the content of the treatise. The reason for this is that the treatise does not so much describe the form of the town as the process for building it, and the process turns out to be emergent. Unless the reader makes the link from process to form, the rules described will make no more sense than the rules for a cellular automaton out of context.

It is tragic that enormous amounts of resources have been spent attempting to recreate the Mediterranean town with no clue as to the underlying source of its complexity. Montreal itself has the world famous Habitat 67, a confusing pastiche of the memories that architect Moshe Safdie brought back from his land of birth, which he had in common with Julian of Ascalon. Habitat 67 was intended to be a low-cost solution to housing, but it never was taken seriously as a model for urban habitat, and its current untrendiness spares it from being labeled fake complexity. That an attempt to emulate the architecture of some of the poorest people of previous centuries would result in an expensive failure testifies to the inadequacy of modern production processes, but also of the wealth inherent in those simple traditional production processes. The beauty resulting from large aggregations of simple buildings has turned many towns into tourist destinations. There is value in process.

The complexity demonstrated by the constructions of pre-modern civilizations may be a direct consequence of their material poverty. Most people will claim that the loss of building quality is a result of culture, and so we must change our own culture through education. That is not a complete answer. Cultures are stored in information technologies and media. The modern era coincides with the invention of printing, making it possible for the first time to reproduce information in large quantities at low costs. As information technologies have progressed and become more affordable, building processes have become increasingly dependent on large amounts of descriptive information, with blueprints describing in every minute detail how to compose a building. And now that CAD software can describe and store nearly limitless information, whole new forms of buildings have become possible.

All of this progress has only enabled builders to become lazier with information. Pre-modern builders, limited to oral communication and their brains to hold information, had to employ very sophisticated means of information compression to communicate and simply remember their cultures. This lead them to rely on simple processes the likes of which are behind the complexity in fractal geometry and cellular automata to build their environments – very short sequences of information that can be utilized to generate fully complex forms. Christopher Alexander even used as an example, in The Nature of Order, the production of a boat that had been coded into a song that the builders recited while creating the boat, adding a mnemotechnical aspect to the storage of cultural information that was essential to pre-modern survival.

Without knowing how traditional cultures were stored, we had no idea how to inspire ourselves from them. Modern and post-modern architects attempted in vain to imitate traditional building using their own, lazy information technologies, and succeeded only in building pastiche of complexity. The breakthroughs in complexity theory of the past decades finally gave us the opportunity to decode the mysteries of historic building cultures by showing us what kind of information to search for. What was right in front our noses suddenly becomes deeply meaningful.

It is to his great credit that Besim S. Hakim went looking specifically for the source of the emergent forms of Mediterranean towns in treatises of building laws. From his study of the treatise of Julian of Ascalon, but also of those of Muslim scholars around the Mediterranean, he was able to identify the underlying process that generates the complex morphology all towns of the region have in common, and that so many have sought to imitate. It is no exaggeration to call this pioneering work in complexity.

The space of Hakim’s search began in the Islamic world, with the treatise of Ibn al-Rami from Tunis in circa 1350. Tracing the origins of the practices described in the treatise, references to treatises written in Egypt, Arabia, Tunisia and Andalusia in previous centuries were researched until the treatise of Julian of Ascalon was uncovered. Written in Palestine to describe the local building customs in order to provide the Byzantine empire with an improved legal system, this particular treatise’s value is its longevity. After propagating throughout Greek civilization as part of a general book of laws (the Hexabiblos), its authority was invoked in decisions dating as recently as the 19th century. Hakim infers the origins of these shared practices, and the shared morphology of regions as far apart culturally, linguistically and geographically, as Andalusia, Greece and Palestine, to customs from ancient Babylonian civilization that had spread to the Eastern Roman Empire.

The goal shared by these treatises is a definition of urbanism as relevant today as it was in Babylon:

The goal is to deal with change in the built environment by ensuring that minimum damage occurs to preexisting structures and their owners, through stipulating fairness in the distribution of rights and responsibilities among various parties, particularly those who are proximate to each other. This ultimately will ensure the equitable equilibrium of the built environment during the process of change and growth. (Hakim, Mediterranean urban and building codes: origins, content, impact, and lessons, p. 24)

Here we see what the underlying error of Habitat 67 was. It was designed as a single static building imitating a process that made a living tissue out of many individual acts of simple building. The codes of the Mediterranean treat the town as a living, whole structure in movement that must be preserved while it achieves equilibrium with a changing environment and society.

Perhaps the most relevant conclusion of this research is the identification of proscriptive and prescriptive rules for building.

Proscription is an imposed restraint synonymous with prohibition as in ‘Thou shalt not’, for example, you are free to design and manipulate your property provided you do not create damage on adjacent properties. Prescription is laying down of authoritative directions as in ‘Thou shalt’, for example, you shall setback from your front boundary by (x) meters, and from your side boundaries by (y) meters regardless of site conditions. Byzantine codes in many instances included specific numeric prescriptions, unlike their Islamic counterparts that tended not to include them. (Hakim, Mediterranean urban and building codes: origins, content, impact, and lessons, p. 26)

A prescription would be a rule that defines in detail what to do in a given situation. A proscription is a template for defining prescriptive rules, a pattern for a rule. Muslim scholars provided mainly proscriptions, but Julian of Ascalon’s treatise was highly prescriptive. Julian was describing in details the local building codes with the idea that they would be used to devise proscriptive rules for the empire. By accident these prescriptive rules became law and remained in force for centuries until their inability to deal with society or physical conditions radically different from sixth century Palestine made them obsolete. Although it means the codes failed to deal with changing circumstances, this gives us the chance to bridge the gap between the physical structure of built towns and the rules that generate them.

The concept of proscriptive rules also helps explain why so many different cultures with specific structural typologies can generate such similar morphology. Hakim uses as an example the problem of views. The Greeks were preoccupied with views of the sea, and their prescriptive rules obliged the preservation of view corridors in new constructions. Muslims, on the other hand, were preoccupied with the preservation of privacy and the prevention of intrusive views from one property to another. This would have very different results structurally, however those two prescriptive rules are based on the same underlying proscription. Local customs and culture could therefore be translated into prescriptive rules using the proscriptions inscribed in building treatises and the emergent morphology of those proscriptions would be symmetric from one culture to the next, while being fully adapted to local conditions.

Another significant fact that strikes out from these treatises is the importance of relationships between neighbors. The Julian of Ascalon treatise describes how to literally embed houses into each other, ultimately making them one continuous, somewhat random building created through iterated steps. But most importantly by proscribing rules as relevant to a neighborhood, Mediterranean urbanism avoids the problem of the absolutist, dare I say “Cartesian” rules of modern planning that are relative to the precisely subdivided lot the building is on. Hakim shows the wastefulness of latter rules in a comparison of the old town of Muharraq in Bahrain with a new subdivision from modern Muharraq.

The town on the left was generated using proscriptions based on neighbors, while the subdivision on the right used absolute rules planned with the subdivision. Notice that the configurations on the right waste much of the space in order to achieve a strictly Cartesian, grid-like morphology that no doubt looks orderly to the planners.

The last item of significance, and perhaps the most revolutionary, is how the proscriptions extracted by Hakim are similar in nature to the rules that Stephen Wolfram described to generate emergent complexity with cellular automata. He himself follows a proscription/prescription system, where the proscription is for example the 2 color, one-dimension elementary cellular automaton that made him famous, for which there exist 256 different prescriptive rules of neighborhood, some of which grow in time to make two-dimensional chaotic fractals. Some urban complexity researchers such as Michael Batty have been playing with cellular automata trying to reproduce urban form, but their efforts have taken them on the wrong track. The codes of historic towns behave in the same manner as a cellular automaton. This should be the focus of their research.

Whatever the potential for research, the proscriptions discovered by Besim S. Hakim are still relevant today and can be used to create the prescriptions that we need to implement an emergent urbanism relevant to the problems of today, that is to say the creation of a sustainable city and living urban tissue out of the vast urban fabric of suburban sprawl. Hakim has so far focused his work on the regeneration of historic neighborhoods by restoring the generative codes that produced them, but there is a vast potential to expand his work to non-historic neighborhoods that are in dire need of new life.

Addendum

Four regions, four cultures, one shared process generating a symmetric morphology

The advent of low-cost motoring and extension of expressways through rural areas made possible a form of urbanisation that few people had foreseen. Le Corbusier had dreamed the automobile to allow the working man to live in the country and work in the city. The suburbs made that dream real, or at least as far as the suburbs were a pastiche of the country. What the automobile did to radically transform rural landscapes was make it possible for someone to live in the country and work a hundred kilometers elsewhere in the country. The possibilities for economic relationships this opened transformed the country into rural cities, gigantically sprawling cities invisible to the naked eye. The fact of this totalistic urbanization of rural land became visible only when building typologies characteristic of the suburbs started appearing in what seemed to be the middle of nowhere. A subdivision of identical houses, or a big box store, surrounded by nothing but fields makes no economic sense unless this subdivision is actually part of a very complex urban tissue. This is what had emerged in the country. Ruralites had all started living urban lifestyles.

Now this urban tissue is being starved of its blood. It is collapsing so fast that everyone can see it happen. Whole businesses who had relied for labor on tens of thousands of square miles of commute regions are seeing their employees beg to be laid off. Loans in vehicles and buildings are going into default. This is what had been predicted for the suburbs. It is happening in the most sprawled city, the countryside, first.

The suburbs can be remodeled to adapt to the post-automobile city, but the rural city is doomed for good. Rural populations are going to migrate into the remaining urban cities, aggravating the drive towards the centers. When we visit the countryside years from now, we will witness the ghost subdivisions and big box stores of the least sustainable development there ever was.